1. Field of the Invention
The present invention pertains generally to wheeled and articulated land vehicles, and more particularly to ball and socket couplings such as may be provided between a towing vehicle and a trailer.
2. Description of the Related Art
Since the advent of mechanized transportation, people have sought better ways to transport matter of nearly all compositions and shapes. In addition to transporting an individual or group of people, there also exists a need for transporting various non-human cargo. In modern times, motor vehicles have provided both human transport and also a motive power source for transporting cargo.
In many cases, the motor vehicle and cargo transport are produced as separable wheeled vehicles. This permits the relatively expensive motor vehicle to be used with or without a particular trailer, thereby allowing the motor vehicle to be used for many diverse purposes. For exemplary purposes only, and not solely limiting thereto, one motor vehicle may be coupled to and detached from at least one trailer. Where a plurality of trailers are available, the motor vehicle may act as the motive power source for only one trailer at a time, or may alternatively be coupled with more than one trailer, such as by linking one trailer to another in the manner of train cars. Where only one trailer is coupled with at a time, any additional trailers may either be stored, or may be parked at suitable location for loading and unloading. These additional trailers may be identical to the first trailer and each other, or may alternatively be different and unique with respect to each other. For exemplary purposes only, one type of trailer may be used to transport heavy loads such as rock and sand, while another very diverse trailer may be used to collect and transport grass clippings and leaves.
Where the trailer is separable from the motor vehicle, both vehicles will ordinarily be provided with at least one wheel set. Separate wheel sets permit the motor vehicle and trailer to each move independently of the other, and so be moved about or retrieved at will. In other words, when desired, a motor vehicle may be disconnected from the trailer to thereby leave the trailer parked, while the motor vehicle continues to travel.
The separate wheel set also allows disparate motion between motor vehicle and trailer, to better accommodate irregularities in the roadway, such as but not limited to potholes. If the two vehicles are not permitted to move at least to some extent independently of each other, there can be enormous damaging forces applied to the coupling between vehicle and trailer. As a result, many modern vehicles have couplings that permit the trailer to articulate relative to the motor vehicle.
One particularly popular coupling is the ball and socket, also referred to as a ball and hitch. One vehicle, commonly the motor vehicle, is equipped with a ball, typically mounted atop a short post. The other vehicle, typically the trailer, is provided with a socket and a way to secure the socket to the ball. Preferably, the socket only encompasses a portion of the ball and is thereby free to rotate not only about a vertical axis through the ball post, but also about a horizontal axis generally parallel to the trailer tongue. Rotation about a vertical axis permits the two vehicles to turn a corner, while rotation about the horizontal axis accommodates road surface irregularities such as potholes.
Through the ages, people have recognized the need for safe transportation. Modern laws and regulations require particular features for a vehicle to be permitted to access public roadways. These laws and regulations, and also various customary requirements and apparatus, have created quite safe roadways that carry millions of vehicles through billions of miles each year.
To ensure safety, roadway approved hitches have various apparatus that not only couple with the ball, but that also can secure the hitch to the ball. These safety hitches tend to be undesirably complex, bulky, heavy, and undesirably expensive to fabricate. As a result, these hitches are not generally used with lighter duty lawn and garden equipment, with All-Terrain Vehicles (ATVs), for light agricultural purposes, or with other similar off-road vehicle and trailer combinations. Instead, most of these lighter applications rely upon a clevis pin that passes through a hole in a trailer tongue. The trailer tongue hole is typically of significantly larger inside diameter than the outside diameter of the clevis pin, which is necessary to enable rotation about more than just a vertical axis.
Unfortunately, the use of a pin passing through an over-sized hole means that there is undesirable play between trailer tongue and clevis pin. This means that changes in relative velocity between towing and trailing vehicle will result in poorly restrained movement between the two vehicles. This can be in the form of “slamming” when the towing vehicle either tries to accelerate or decelerate, or even during cornering. In addition to the unpleasant noise, there is also the potential for significant wear and damage to both the trailer tongue and the clevis pin at the point of engagement there between. Further, the rather continuous noise produced by the impacts between trailer tongue and clevis pin can mask more serious sounds that should demand the immediate attention of the vehicle operator or a suitably trained person.
Exemplary U.S. patents that illustrate various hitches and couplings, the teachings and contents which are incorporated herein by reference, include U.S. Pat. No. 2,326,466 by Kitterman, entitled “Trailer Coupler”; U.S. Pat. No. 2,407,464 by Wilson, entitled “Trailer Hitch”; U.S. Pat. No. 3,139,291 by Geresy, entitled “Trailer Hitch Locking Device”; U.S. Pat. No. 3,831,982 by Bernhardt et al, entitled “Universal Coupling”; U.S. Pat. No. 4,072,320 by Powell, entitled “Coupling Element for Trailer Hitches”; U.S. Pat. No. 4,209,184 by Byers, entitled “Self-locking Trailer Hitch Assembly”; U.S. Pat. No. 4,241,936 by Carruthers et al, entitled “Trailer Couplings”; U.S. Pat. No. 5,344,174 by Sanders, entitled “Trailer Coupling with Friction Damper”; and U.S. Pat. No. 5,671,938 by Olson, entitled “Implement Hitch”.
Another patent, illustrating a different coupling technique using a cam apparatus, is shown in U.S. Pat. No. 2,673,096 by Bendtsen, entitled “Hitch Mechanism”, the teachings and contents which are incorporated herein by reference. In addition to the aforementioned patents, Webster's New Universal Unabridged Dictionary, Second Edition copyright 1983, is incorporated herein by reference in entirety for the definitions of words and terms used herein.